Long Term Evolution (LTE) is expanding its utilization in Unlicensed National Information Infrastructure (U-NII) bands by deploying technologies like LTE Unlicensed (LTE-U) and Licensed Assisted Access LTE (LTE-LAA). However, deploying LTE in unlicensed bands can cause WiFi systems, which are the incumbent systems in U-NII bands, to experience interference. Not only do these radio technologies (LTE and WiFi) not understand each other but in absence of a carrier sense (preamble detect), LTE's coexistence mechanism relies only on Energy Detect (ED) to share a channel. The problem is even more acute in regions where Listen before Talk (LBT) is not mandatory for LTE systems, leading LTE systems to gain access to shared channels more often than WiFi systems since WiFi systems are “polite” and implement random back off.
In order to avoid performance degradation, Wi-Fi Access Points (APs) should ideally try to avoid channels where LTE-U and/or LTE-LAA interference is detected. However, if the AP is configured to operate in wider bandwidths such as 80 MHz or 160 MHz bandwidths, the number of alternative channels available to the AP to select from is limited. While lowering the bandwidth of the AP is an option, it potentially wastes large chunks of the spectrum. Additionally, LTE devices and systems are known to use unlicensed spectrum in an “on-demand” basis. Therefore, completely avoiding channels with LTE-U and/or LTE-LAA interference reduces WiFi channel availability to the WiFi APs, increases spectrum overlap, decreases air time efficiency and reduces overall network capacity.